Method of making glass-ceramic pump parts

ABSTRACT

THIS INVENTION IS A METHOD OF PRESS-FORMING THERMALLYCRYSTALLIZABLE GLASS MATERIAL, HAVING A HIGH VISCOSITY CHARACTERISTIC, INTO PUMP PARTS WHEREIN THE MATERIAL IS HEATED TO A MOLTEN STATE AND PRESS-FORMED INTO PUMP PARTS HAVING INTRICATE WATER-WAY DESIGNS AND A SOLID DISCHARGE NOZZLE, AND A CORING OPERATION THAT COMPLETES A PASSAGE IN THE DISCHARGE NOZZLE, THE GLASS IS THEN HEATED AND CRYSTALLIZED TO A CERAMIC STATE, KNOWN AS A GLASS CERAMIC.   D R A W I N G

June 18, 1974 YU K. PE!

IETHOD OF MAKING GLASS-CERAMIC PUMP PARTS Original Filed Oct. 12; 1970III! 2 sheets-sheet 1 FIG, I

Y KIDIEI BY F DWYER 5.5- HOLLE'R ATORM'ZQSI JunglS, 1974 YU K. PE! 3,17,732

METHOD OF MAKING GLASS-CERAMIC PUMP PARTS Original Filed Oct. 12; 1970 2Sheets-Sheet 3 l h MWN V v CooLme REEF] CURMG Foam (\LG CKQSTAL (Zr-10MINVENTOR.

' BY gram/ ER g 3f HQLLE'K United States Patent Office 3,817,732Patented June 18, 1974 ABSTRACT OF THE DISCLOSURE This invention is amethod of press-forming thermallycrystallizable glass material, having ahigh viscosity characteristic, into pump parts wherein the material isheated to a molten state and press-formed into pump parts havingintricate water-way designs and a solid discharge nozzle; and a coringoperation that completes a passage in the discharge nozzle. The glass isthen heated and crystallized to a ceramic state, known as a glassceramic.

CROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation of application Ser. No. 80,111, filed Oct. 12, 1970, nowabandoned, which was a continuation-in-part of application Ser. No. 78,-476, filed Oct. 6, 1970, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to a method of forming pump parts from a thermallycrystallizable glass material by press-forming. Glass ceramic materialis most desirable for pump parts because of its characteristics, whichinclude a high resistance to acid etching and a very low coefiicient ofthermal expansion; however, the viscosity characteristics of thermallycrystallizable glass materials make it impractical to cast parts in sandmolds.

Description of the prior art Pump parts of non-ceramic material havebeen cast in sand molds. This sand mold casting involved the pouring ofa molten material into a mold made in a mirror image of the part, andallowing the molten material to cool. However, the high viscosity ofceramic materials make it difficult to form intricate designs.

This invention is a method of forming pump parts from a thermallycrystallizable glass, using a press-forming operation.

In this method, the thermally crystallizable glass is pressed to form apump casing, including the discharge nozzle of the pump.

The formed pump casing is then cored to form a discharge for thewater-way.

SUMMARY OF THE INVENTION It is desirable to make pumps from glassceramic materials because they have desirable physical characteristicsincluding high thermal shock resistance, a low coefiicient of thermalexpansion and a high resistance to acid-etching; however, it isdiflicult to form intricate designs, especially a nozzle.

This invention is a method of forming pump parts from a thermallycrystallizable glass, using a press-forming operation. Mostglass-ceramics have a low coefiicient of thermal expansion and possessadequate tensile strength, but have a high viscosity index at meltingtemperatures; therefore, the material is not suitable for a castingprocess. The method of this invention permits the forming of the highviscosity molten material,

especially glasses having a viscosity of 10* poises at temperaturesbelow 2000" F.

In this method, the intricate water-way, whether it is a single ormultiple path, can be pressed into the casing and also form thedischarge nozzle of the ceramic pump.

The formed casing is then cored to form a discharge water-way. The glassis then crystallized by heating.

DESCRIPTION OF THE DRAWING FIG. 1 is a side sectional view of a mold anda pump casing being formed by the contours of the mold. FIG. 2 is a topview of a casing. FIG. 3 is a block diagram of the method.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, FIG.1 shows a mold and a pump casing being formed of a thermallycrystallizable glass of high viscosity. The casing is circular inconfiguration and has a hollow portion for housing an impeller and awater-way which has a semi-circular configuration, and which runs aroundthe outer periphery of the casing.

Referring to the drawings, FIG. 1 shows a mold 10, a pump casing 11being formed in the mold. The casing is a glass ceramic material formedof a heat-crystallizable glass of a high viscosity. The casing 11 iscircular in configuration and has a hollow portion 13 housing animpeller; a water-way 14 having a semi-circular configuration, occupiesan area around the outer periphery of the casing. A discharge nozzle 15is formed of solid material. A water passage, shown by dotted lines 16,is opened by a subsequent coring operation. In the coring operation, itis necessary to use a diamond-tipped drill, which is water lubricatedand then cooled. Referring again to FIG. 1, a ram 17 has the shape ofthe inner configuration of the casing.

A complete description of the steps of the method of this invention maybe had when the following description is read in conjunction with theFIG. 3 of the drawing.

Thermally crystallizable glass compounds and methods of crystallizingglass ceramics, therefor, are disclosed in US. Patent Application, Ser.#630,507, filed Apr. 13, 1967, to Petticrew, Richard W.; andsubsequently disclosed in the corresponding streamlined continuationapplication, Ser. #866,168, filed Oct. 13, 1969. The aboveidentifiedapplication is now US. Pat. No. 3,625,718.

A typical example of a heat-crystallizable glass composition is thefollowing, having this composition in parts by weight as follows:

EXAMPLE I SiO; 7 A1 0, 1 Li O ZnO TiO; ZI'Og N330 K 0 F room temperatureand is then removed. At this time, the coring operation is performed,forming the discharge opening, as shown in FIG. 2. Parts of the moldedpiece are then machined to provide a desirable, smooth surface formating with the casing cover and also with a piping system leading fromthe discharge outlet. The formed and machined part is then placed in anoven and heated to a final temperature of about 2000 F., in accordancewith a heating schedule as disclosed in application, Ser. #866,168.

The formed pump part is placed in an oven and heated to a finaltemperature of about 2000 F. The heat treatment is that described in theabove disclosed Petticrew applications 630,507 et al., wherein theformed heatcrystallizable glass is heated from room temperature atapproximately 50 per hour to about 1350 C. A holding period follows forabout 16 hours; thereafter, the temperature is raised at about 10 perhour to about 1450" C. Subsequently, at 150 per hour, go to 1950 C. Thenat 50 per hour to about 2000 where the temperature is held forapproximately 1% hours. The formed material is then cooled down at about300 per hour. The heating schedule varies with the composition of theheat-crystallizable glass. This schedule is for Example I herein. Theglass has a log viscosity at temperatures below about 2490 F. Otherexamples of heat-crystallizable glass compositions are shown in Table H.

TABLE II Composition, parts by weight, and glass properties Theexplanation of the symbols in Table II is:

AP=Annealing point temperature L .-=Temperature at which the logarithmof the glass viscosity in poises is four (4).

What is claimed is:

1. A method of making a pump casing comprisingpressing a charge ofthermally crystalilzable glass having the following range ofcompositions:

said composition having an annealing point ranging from 1150 C. to 1260C. and a log viscosity in poises equal to 10 at temperatures rangingfrom 2400 F. to 2505 F. against the confines of a mold to form thecharge of molten glass into a casing having an imperforate bottom Walland an imperforate peripheral wall defining a hollow chamber, a waterdischarge way being formed in a portion of said hollow chamber, a solidprojection from a peripheral edge of the chamber forming a dischargenozzle extending radially outward from said peripheral wall, (b) coolingsaid pressed casing to ambient temperature and (c) coring said radialprojection to define a radial discharge passage in said nozzle and (d)thereafter subjecting the formed and cored article to a heat treatmentto crystallize the glass.

References Cited UNITED STATES PATENTS 2,648,179 8/1953 Manes et a1.51283 3,455,666 7/1969 Bazinet Jr. 61 X 3,113,877 12/ 1963Janakirama-rao 6533 3,613,222 10/1971 Richey 6561 X 911,809 2/1909Conradson 51--283 3,113,009 12/ 1963 Brown et al. 6533 OTHER REFERENCESHandbook of Glass Manufacture, Fay T. Tooley, pp. 192-199.

FRANK W. MIGA, Primary Examiner US. Cl. X.R. 6561 2222 8? I i STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patflg No; 3 .8l7.732 Dated June18; 1974 Q d Inventor(s) LU K. PEI

ars in the above-identified patent It is certified that error appe 5shown below:

and that said Letters Patent are hereby corrected a Col 4, line 2 after"comprising" add (a) Signed and sealed this 3rd day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. Attesting Officer c. MARSHALL DANN. Commissioner ofPatents

